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July 13, 2009 -- Condom use reduces, but does not eliminate, the risk of contracting genital herpes, according to a new review of research.

Researchers found consistent condom users have about a 30% lower risk of contracting genital herpes than those who never used condoms.

While earlier studies have shown that consistent condom use can substantially reduce the risk of HIV and other sexually transmitted infections (STIs), their effectiveness at preventing the spread of herpes simplex virus 2 (HSV-2) is less certain.

HSV-2 is the virus that typically causes genital herpes, a lifelong viral infection. Transmission of HSV-2 is mainly from skin contact in areas that may not be covered by a condom.

"Although the magnitude of the protective effect was not as large as has been observed with other STIs, a 30 percent reduction in HSV-2 incidence can have a substantial benefit for individuals as well as a public health impact at the population level," writes researcher Emily T. Martin, MPH, PhD, of Children's Hospital Research Institute and the University of Washington, Seattle in the Archives of Internal Medicine.

Researchers analyzed information from six studies on condom use and HSV-2 to determine the effectiveness of condoms in preventing the virus; the study involved more than 5,000 people.

The results showed that people who used condoms 100% of the time had a 30% lower risk of contracting genital herpes.

Among less consistent condom users, the risk of HSV-2 infection decreased by 7% for every 25% increase in condom use during vaginal or anal sex. Conversely, the risk of contracting genital herpes increased significantly with the frequency of unprotected sex acts.

Researchers found no significant differences between men and women in the level of protection against genital herpes that condom use offered.

"Based on findings of this large analysis using all available prospective data, condom use should continue to be recommended to both men and women for reducing the risk of HSV-2 acquisition," write the researchers.